OBJECTIVES: To demonstrate why microsimulation modelling of colorectal cancer screening indicates that there are likely gains to be made by reconfiguring BowelScreen, Ireland's national colon cancer prevention programme. This analysis aims to show how the omission of relevant alternative screening strategies in a prior cost-effectiveness analysis of colon cancer screening in Ireland has likely led to a sub-optimal policy and that better outcomes at lower cost can be achieved by using a lower quantitative cut-off in the faecal immunochemical testing (FIT) employed.

METHODS: We used the MISCAN microsimulation model of colorectal cancer screening to simulate the costs, effects and follow-up colonoscopy capacity requirements of 144 alternative screening strategies. These varied in their start and stop ages, screening intervals and FIT quantitative cut-off levels. Included in the simulations are Ireland's current programme of biennial screening of 60-69 year-olds using a FIT cut-off of 225ng/ml of haemoglobin. We simulate strategies with FIT cut-offs as low as 50ng/ml. The resulting estimates are plotted in the cost-effectiveness plane, checked for dominance and incremental cost-effectiveness ratios are calculated.

RESULTS: We find that a combination of a reduction in the FIT cut-off to 50ng/ml, an extended screening interval of 3 years and a reduced screening start age of 55 saves 20% more QALYs, reduces costs by 7%, and yields a 17% reduction in colonoscopy requirements. In general, employing a lower FIT cut-off dominates strategies with higher cut-offs, such as those currently employed in BowelScreen. While extending the screening programme to a larger population would be possible and more cost-effective, it requires a lengthening of the screening interval from two to three years.

CONCLUSIONS: Very simple changes to BowelScreen could save many more lives annually, reduce costs and relieve pressure on already constrained colonoscopy capacity. This simulation evidence suggests that BowelScreen should be re-examined.